JPH0712923Y2 - Gas introduction path for GC-IR - Google Patents

Description

[Detailed Description of the Invention] (a) Industrial Application Field The present invention relates to a gas introduction path for GC-IR. More specifically, it relates to a gas introduction path of a device (GC / FT-IR) for measuring an infrared absorption spectrum of a gas sample separated by a gas chromatograph (GC) by a Fourier transform infrared spectrophotometer (FT-IR).

(B) Conventional technology In GC / FT-IR, a gas introduction path that links GC and FT-IR is connected to a GC column and a fused quartz tube that introduces a gas sample separated by the column into an IR measurement cell. A metal pipe that covers the outer periphery of the fused silica tube and a sheath heater that is provided in contact with the outer side of the metal pipe are mainly used, and the sheath heater that is covered with a heat insulating material is used. The gas sample transferred in the quartz tube in the gas introducing tube having such a configuration is kept in a heated state by heat conduction and heat radiation from the sheath heater through the metal pipe and the quartz tube wall.

On the other hand, in the case of GC / FT-IR, the gas sample to be measured that is introduced into the cell has an infrared absorption spectrum measured in the state of being mixed with a make-up gas consisting of an inert gas such as nitrogen at the cell inlet. Therefore, it is necessary to control the flow rate of the makeup gas, control the heating, and the like.

(C) Problems to be solved by the device However, in the gas introduction path having the above-described configuration, since the heat capacity is large at the connection part of the metal pipe, the entire flow path system of the gas sample is heated by the heater having an even load capacity. In this case, a temperature drop occurs at this connecting portion to serve as a cooling point, and the high temperature separation component gas is adsorbed in the fused silica tube corresponding to this portion, which causes deterioration of the fused quartz tube. Further, a temperature distribution is generated in the fused silica tube, and the separation component gas is adsorbed and diffused in the fused silica tube, which causes a decrease in the degree of separation.

The present invention has been made in view of such a situation, and an object thereof is to provide a gas introduction passage having an even temperature distribution.

(D) Means for solving the problems Thus, according to this invention, a gas chromatograph (GC)
Connect the infrared absorption spectrum (IR) measurement cell to the GC
A gas introduction path configured so that the gas sample separated by the above can be introduced into the cell while keeping the heating state, and is connected to the column of GC to introduce the gas sample separated by the column into the cell. Along the outer circumference of the inner tube, an outer tube that covers the circumference of the inner tube and transfers an inert gas heated to a predetermined temperature along the outer side of the inner tube to introduce the inert gas into the cell. There is provided a gas introduction path for GC-IR, which is composed of a heating means provided.

According to this invention, the heating means for the gas sample comprises a heating gas flow layer provided in contact with the outside of the gas sample transfer inner tube, and a normal heating means provided outside the flow layer through a tube wall. It is characterized by having a double structure.

In this invention, an inert gas is used as the circulation heating gas, and the gas is selected so that it can be used as a makeup gas for infrared absorption spectrum measurement in addition to the above heating applications, for example, nitrogen or helium. Etc.

The above-mentioned inert gas must be supplied while controlling the heating temperature and flow rate, but a control mechanism for this may be set independently, but the above-mentioned inert gas is the carrier gas of a gas chromatograph (GC). It is possible to use the same kind of gas as the above, therefore, by branching the carrier gas supply channel in the GC, it is configured to be used as the heating inert gas of the present invention by utilizing the heating / flow rate control on the GC side. It is preferable. As the heating temperature of the inert gas, a temperature at which the gas sample transferred through the inner tube does not cool and precipitate on the way to the IR measurement cell is selected.

The inner tube used in this invention is preferably constructed by extending a fused silica column of GC, and the outer tube is preferably made of metal in terms of thermal conductivity, but is not limited to these. Not done.

(E) Action According to the present invention, an outer tube that connects the gas chromatograph (GC) and the infrared absorption spectrum (IR) measuring cell and is provided with heating means on the outer periphery, and is inserted and disposed in the outer tube. Done GC
The inert gas heated to a predetermined temperature is transferred to the communication path from the inside of the GC to the inside of the IR measurement cell, which is formed by the gap between the gas sample separated by the column and the inner tube that introduces it into the measurement cell. As a result, heat conduction / heat radiation by the heated inert gas and the heating means is performed over the entire flow path from the GC column of the gas sample transferred in the inner tube to the cell, and the gas sample from the GC to the cell is The heated sample is uniformly heated and transferred, and the heated inert gas is mixed with the gas sample as makeup gas in the measurement cell.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

(F) Embodiment FIG. 1 is a structural explanatory view of an example of the gas introduction path for GC-IR of the present invention. In the figure, the gas introduction path (1) connecting the gas chromatograph (GC) side and the infrared absorption spectrum (IR) measurement side is extended from the separation column (7) in the GC oven (6), and an IR measurement cell is provided. The inner tube (2) made of fused silica inserted into the gas introduction tube (81) of (8) and the end of the gas introduction tube (81) of the cell having an open end (a) inside the GC oven A metallic outer tube (3), into which the fused quartz inner tube (2) is inserted, and a sheath heater (4) wound around the outer tube along the outer tube (3) and the sheath heater ( Temperature controller (5) that heats 4) to a predetermined temperature
It is mainly composed of and. The sheath heater (4) is covered with a heat insulating material (not shown), and the outside thereof is protected by a metal pipe (9).

The IR measuring cell (8) has a cylindrical light pipe (82) which has a window material capable of transmitting infrared rays at both ends and is hermetically sealed, and a cylindrical wall near each end of the light pipe (82). A gas inlet pipe (81) and a gas exhaust pipe (8
3) and a heating block (84) for heating the light pipe, the gas introduction pipe and the gas discharge pipe,
Further, there are provided a pair of infrared interference light sources (not shown) and a condenser (not shown) that transmit through the light pipe in the axial direction, and an infrared detector (not shown).

The fused quartz inner tube (2) has an inner diameter of 0.1 to 0.3 mm and an outer diameter of 0.2 to
On the other hand, the outer metal pipe (3) is 0.4 mm, but the stainless steel pipe with an inner diameter of about 1 mm is used, and the open end (a) of the metal outer pipe flows from the carrier gas supply part of the GC. A makeup gas supply path (11) shunted through the controller (10) and a connector (1) as shown in FIG.
Connected by 2). The connector (12) is a cylindrical body having one end connected to the opening end (a) and the other end penetrating the fused silica inner tube (2), and makeup gas is supplied to the body of the cylindrical body. The passages are connected and the penetrations are sealed from inside the cylinder with graphite phenol (13). The inner tube (2) made of fused silica inserted in the gas introduction pipe (81) of the IR measurement cell is arranged with a gap in the gas introduction pipe and is opened at the cell inlet.

In the GC-IR using the gas introduction path (1) of the present invention configured as described above, the sheath heater is heated to a predetermined temperature by the temperature controller and is in contact with the sheath heater by heat conduction from the sheath heater. The metal outer tube is heated, and the heat radiation from the outer tube heats the fused silica inner tube inserted into the outer tube. On the other hand, GC
The carrier gas diverted from the carrier gas supply unit on the side is sent to the makeup gas supply passage in the GC oven at a predetermined flow rate. The carrier gas (make-up gas) heated to the oven temperature in the flow path passes through the connector from the supply path and flows through the gap between the inside of the fused silica inner tube and the inside of the metal outer tube heated as described above. It is then transferred along the outside of the inner tube and then introduced into the cell through the gap between the gas introducing tube of the IR measurement cell and the inner tube. Here, in the makeup gas flow path from the connector to the IR measurement cell, the heating state of a uniform temperature distribution is maintained in the entire flow path due to the flow of the heating makeup gas and the heat conduction from the sheath heater. In this state, the gas sample separated by the separation column is sequentially transferred in a fused silica inner tube continuous with the column at a predetermined carrier gas flow rate at a predetermined temperature, and is introduced into the IR measurement cell from the tip of the inner tube. . While being transferred in the inner tube, the gas sample is uniformly heated from beginning to end due to heat conduction and heat radiation of the heating makeup gas flowing in contact with all the outer walls of the inner tube.

(G) Effect of the device According to this device, the GC is connected to the IR measurement cell and the GC is connected.
The gas introduction path for transferring the gas sample separated by the column to the IR measurement cell has a uniform temperature distribution, that is, no cooling point is generated, so that the transferred gas sample is not adsorbed in the fused quartz tube. The deterioration of the quartz tube can be prevented, and the deterioration of the degree of separation due to the adsorption / diffusion of the gas sample in the fused quartz tube can be avoided. The heating device for make-up gas, flow rate control, etc. can be controlled by the accessory on the GC side, and the system can be simplified.

[Brief description of drawings]

FIG. 1 is an explanatory view of the configuration of an example of a gas introduction path for GC-IR of the present invention, and FIG. 2 is a connection state of the fused silica inner tube, the metal outer tube and the makeup gas supply path of FIG. FIG. (1) …… Gas introduction path, (2) …… Fused quartz inner tube,
(3) …… Metal outer tube, (4) …… Sheath heater,
(5) …… Temperature controller, (6) …… GC oven,
(7) …… Separation column, (8) …… IR measurement cell,
(9) …… Metal pipe,

Claims (1)

[Scope of utility model registration request] 1. A gas chromatograph (GC) and an infrared absorption spectrum (IR) measuring cell are connected to each other so that a gas sample separated by the GC can be introduced into the cell while maintaining a heated state. A gas introduction path, which is connected to a GC column and introduces a gas sample separated by the column into the cell, and a predetermined temperature along the outside of the inner tube that covers the circumference of the inner tube. A gas introduction path for GC-IR, comprising an outer tube for transferring the introduced inert gas and introducing it into the cell, and a heating means provided along the outer circumference of the outer tube.